The use of radio frequencies is controlled by national and international bodies and such frequencies generally cannot be used without licenses from the appropriate governing bodies that control various specific uses of those frequencies. To avoid interference with licensed frequencies, these governing bodies often do not license portions of the spectrum adjacent to areas that are licensed. The term “white space” is used to refer to these unused radio frequencies within the electromagnetic spectrum.
White space may also exist simply as a result of radio frequencies that have never been, or are no longer being, licensed or used. As an example, the FCC's planned change to digital television may create large areas of white space. On Nov. 4, 2008, the FCC voted to permit use of certain white space frequencies without licenses. (See “FCC White Spaces Decision Kicks Off the Next Wireless Revolution”, Nov. 5, 2008, http://blog.wired.com/gadgets/whitespaces/index.html, retrieved on Dec. 8, 2008).
The availability of free, unregulated spectrum could create new technologies and new markets for bringing fast wireless internet connectivity to the masses. However, wireless microphones and other equipment used by broadcasters, theater producers, schools and houses of worship already use some of this spectrum. These groups of wireless microphone users have expressed concern that the unlicensed and unregulated use of certain regions of the radio frequency spectrum may be a source of interference with their wireless microphones.